Esters of methacrylic acid



Patented se als, 193s UNITED STATES "PATENT orr ca E. I. du Pont de Nemours a Company, Wil mington, Del., a corporation of Delaware No Drawing. Application July 14, 1934;

4 Serial No. 135,275

- B'Claiim- (Oi. 260-2) The present invention relates to new materials, which are useful in the art, toesters oi methacrylic acid, and more particularly to the.

esters of methacrylic acidwithaliphatic monohydric saturated secondary alcohols.

An object of the present invention is toprovide a new composition of matter and a process for its preparation. A further object of the invention is to provide a new polymerizable composition of matter together with a process for itspolymerization. A still further object of the invention'is to provide a process for the preparation oi the methacrylic acid esters of the allphatic monohydric saturated secondary alcohols,

is which may be obtained by the reaction of the secondary alcohol with a methacrylyl halide. Anotherobject of the invention is to provide mixtures or interpolymers -oi the polymerized resin with other polymerizable compounds of methacrylic and acrylic acids. Other objects and advantages of the invention will hereinafter appear.

There have been prepared in accord with this invention valuable esters of methacrylic acid.

which have been found useful as prepared and even more valuable when polymerized. These compounds may be. generally described as methacrylic acid esters of the alphatic monohydric saturated secondary alcohols such, for example, as

so dimethyl, methyl ethyl, diethyl, methyl propyl,

ethyl propyl, ethyl isopropyl, dipropyl, diisopro- -pyl,'propyl butyl and equivalent carbinols which may be substituted or unsubstituted by halogen ,or other substituent group; the methacrylic acid esters of the higher secondary alcohols are likewise included as, for example, 3-methyl pentanol-2, 2-methyl pentanol-3, and in fact any secondary alcohol having the structural formula" cnon ' R I 4 .in which R1 and R: may be similar or dissimilar alkyl, aryl, or aralkyl groups.- I f The following specific examples are furnished to illustrate methods of preparing my new compositions of matter but it will be understood that the invention is not limited to the details therein The methacryiates, as prepared in accord with given. Example 1.-'-Equimolar quantities oi methacrylyl chloride and diisoprop l carblnol. were mixed and, the solution was warmed on a water,

bath under a reflux condenser atsuch a rate that hydrogen chloride was liberated vigorously.

is After the vigorous liberation of hydrogen chloof methacrylyl chloride ondary butyl alcohol were mixed and the solusolved in ether,

ride had ceased (usually'after the solution' had 'chloride and heating on bath was continued 5 about IO'minutes longer.

.Aitercoolin8, the reaction mixture was dissolvedjin ether, and extracted-'with-water and then with 5%I s0diilm hydroxide solution until free fronr'hydrochloric acid, inhibitor and unreacteddiisopropyl carbinol. The cold reaction mixturewas neutralized and then washed and dried over a suitable d'esiccating medium. The solvents were removed from the dried productby fractional distillation, and the ester finally s separated by fractionation under reduced pressure. A yield of di-isopropyl carbinol methacrylate was obtained. This ester had a boiling point oi '12-'75 C. at 9 mm., and a density-at 20 Example 2.-104 parts (parts-are all by weight) and [4 parts 015 section was warmed on a water bath under a reflux condenser at such a rate that hydrogen chlo- 25 I ride was liberated vigorously. After the vigorous liberation of hydrogen chloride had ceased (usually after the solution had been heated on the boiling water bath for about one-half an hour) there was added 10 parts of hydroquinone to each parts or methacrylyl chloride used and heating on bath was continued about 20 minutes longer. After cooling, the reaction mixture was disthen with 5% sodium hydroxide solution until free from hydrochloric acid, inhibitorand unreacted secondary butyl alcohol. The cold reaction mixture was neutralized and then washed and dried over a suitable desiccating medium. The' solvents were removed from the dried product by fractional distillation, and the ester finally separated byrractionation under reduced pressure. A 45% yield of secondary butyl methacrylate'wasobtain This ester had a boiling 45 point' or 53-5'P C. at 18 a density or 0.890 I at 20 0., and a saponiflcation number of 406.4,- theoretical 395. 1

sometimes be solids. The estersas thus produced are monomeric and may be polymerized,

according to the invention, by means or heat. light, and/or a catalyst, e.g., as described .ior the polymerization, of organic vinyl esters in 55 and extracted with water and 35 fate, boron fluoride, the mineral acids, e. g., hy-

drochloric and sulfuric acids as well as the organic acids, for example, acetic, and methacrylic acids, etc., as well as the anhydrides and acid halides of such organic acids, metal salts of fatty acids and resinic acids, e. g., cobalt linoleate and resinate, manganese oleate and rosin, etc. The polymerization may be eil'ected inthe presence or absence of a, solvent for both monomer and polymer, or in the presence of a. solvent for the monomer and a non-solvent'for the polymer,' or the monomer may be emulsified and then polymerized. Preferably polymerization is carried out at a, moderate temperature, i. e., between 60-100 C., altho higher temperatures, such as, for example, 130 C., or higher, may be em-.- ployed. The polymerization reaction is usually strongly exothermic and it may be necessary to control the temperature by cooling devices, tho polymerization may be carried out in apparatus which may or may not be provided with condensing devices. or in suitable pressure equipment.

As indicated, various methods may be employed for polymerizing the monomeric esters of methacrylic acid and it has been found that the properties of the resins, the physical properties to a large extent and the chemical properties to a lesser extent, are altered considerably by the type of polymerizing process utilized.' The process described in the copending applications of D. E. Strain, Ser. Nos.'668,080 filed April 26, 1933, and 704,753 filed Dec. 30, 1933, may be used, if desired.

Methods illustrating the polymerization of the esters will now be described, but it will be understood that other suitable polymerizing processes may be employed.

Example 3.40 parts (parts are given by weight) of diisopropyl methacrylate monomer was dissolved in 250 parts of methanol in a bottle provided with a stopper, then 0.4 part of powdered benzoyl peroxide was added {to this solution. After the benzoyl peroxide was all dissolved, parts of water, insuflicient to cause permanent turbidity, was added. The bottle was securely closed and set in an oven at approximately 65 C. 'After the polymerization was complete in approximately 18 days, the mixture was allowed to cool. The liquid was decanted. The

small pieces, anddried in a vacuum desiccator. A 60% yield of a white, semi-fused, brittle resin was obtained, soluble in butyl acetate, gasoline, and toluene, relatively insoluble in acetone. The resin was placed in a disk shaped mold in which it was subjected to a temperature of C. and a pressure of approximately-5,000; pounds ,per square inch for approximately 15 minutes. A

molded clear, colorless; and very brittle disk was obtained which softened at a temperature of 60 C. A 5% solution in, toluene had a viscosity at 25 C. of 0.01 poise. a

Example 4.-'Ihe polymerization processof Example 3 was repeated using, 44- parts of secondary butyl methacrylate monomer, ,3 00"parts of methanol, 0.4 part of. benzoyl peroxida'andtoparts of water. After 2; days at'65 C. an 89% yield of the polymerized esterwasobtained as a semi fused mass which could bereadilygr'ound to a powder. The resin gasoline, acetone, and toluene, had a Viscosity was spread on a glass was soluble inbutyl acetate,

of 0.018 poise (5% solution in toluene at 25 C.), and was compatible with nitrocellulose. The compatibility with nitrocellulose was determined by dissolvingan equal volume of a 5% toluene solution of the polymerized ester in a solution consisting of 20 parts of nitrocellulose and 380 parts of butyl acetate. The resulting solution plate and allowed to dry at room temperature. The resin was placed in a disk shaped mold in which it was subjected to a temperature of 100 C. and a pressure of approximately 5,000 pounds per square inch for approximately 15 minutes. A molded water clear disk was obtained which softened at a temperature of 62 C.

Valuable products may be obtained by utilizing the polymers of thees'ters described herein together with equivalents or homologues thereof admixed with other polymeric acrylic or methacrylic esters or other derivatives. Especially valuable products result if the monomeric esters are mixed prior to their polymerization; by this method interpolymers having a wide range of characteristics are made. Due to the unique characteristics of methyl methacrylate polymer, which is a hard resin having a high melting point, its admixture with the, polymeric esters of methacrylic acids herein described or interpolymers thereof are particularly well adapted for many uses.

The esters of methacrylic acid as well as mixtures orinterpolymers thereof with other polymerizable compounds are particularly well suited for thermoplastic molding. The monomer may be polymerized and/or preformed prior to plac ing in the mold and then may be molded in accord with the usual procedural steps employed particularly in the molding of methyl methacrylate as described in the Rowland-Hill Patent 1,980,483, of November.1 3, 1934. The mold preferably is hot, prior to the introduction of the polymerization product, :is then closed and the material so.confined heated and pressed, the temperatures ranging from approximately 80 0., and pressures from 200'pounds per square inch upward -are usually sufiicient to give a suitably molded product. The presence or absence of plasticizers will, of course,-alter considerably the cal characteristics of the resulting product to fit the particular need for which the molded article is to be used. resin was removed from the bottle, was cut into The masses resulting from polymerization can immediately (1. e., in the states they have been obtained)- be made into useful articles. It is possible to obtain the required articles if, for instance, the polymerization be carried out while the initial material is in a suitable mold, for instance, one of steel or glass, so that the articles, for example, umbrella handles, fountain pen barrels,'buttons, and the like, are obtained directly from the mold. Or, if desired, the masses may be worked to the required shape by softening with suitable softeners or plasticizers in the presence of volatile solvents and, after shaping, evaporating the solvent.

The polymerization products may be worked into the required shapes in various ways, for

or theymay be pressed into the required shapes such as buttons, combs, and the like.

1 able solvent which may or may not be the mono- The solid masses can be worked by cutting, sawing,'flling, or the like, whether they be ob tained directly by polymerization, or after special treatment of the polymerized masses. These shaped articles may be polished, and parts connected together by smearing the faces to be connected with a suitable solvent, such as acetone,

epichlorhydrin, or the corresponding methacrylic acid ester. r

The polymerization product dissolved in a suitmer maybetransiormed into a useful article, e. g., films, by casting and then evaporating the solvent, or by extrudingthru a suitable orifice into i a precipitating bath or drying atmosphere. The polymer may be recovered from such solutions by precipitationwith a sui ble non-solvent for f the polymer.

and using them in The properties of the resulting masses may be widely varied by modification with plasticizers, e. g., dibutyl' phthalate, tricresyl phosphate, etc., drying, semi-drying, and non-drying oils, synthetic and natural resins, waxes, bitumens, cellulose derivatives, e.' g.,'cellulose nitrate and ethyl cellulose, etc., pigments, Thus, it is possible to produce, instead of hard glass-like masses, also soft and flexible masses. Likewise, .by the addition of suitable coloring means, it is possible to produce masses, or objects,

having any desired color effects. The incorporation of the additions can be effected either before, or during, the polymerizing process, or the additions can be made to the already formed polymerization products in a suitable condition.

If the polymerization of an organic methacrylic acid ester be carried out ,in an incomplete manner, a syrupy solution of the polymerization product containing some unchanged methacrylic acid ester is obtained. This product can be utilized either directly or along with other solvents or diluents for the production of substances to, be

used for coating, painting, or impregnating purposes. If, for instance, a porous substance such as wood, paper, textile fabric,

and impregnations are obtained on completing the polymerization of the coating, painting, or impregnation, for instance by exposing the article to artificial or natural light, or by heating it, or by employing both light and heat. In this case a portion of theunchanged methacrylic acid ester in the syrupy'solution may or may not be evaporated while another portion may be converted into the solid polymerization product. The articles.

thus treatedhave imparted to them a very high resistance to external influences, e. g., resistance to water, acids, alkalis, and atmospheric-changes.

The said syrupy mass can minuted matter, such, for instance, as ground cork, or ground wood, fibrous substances, mineral fillers, or the like, and the mixture be made into the proper shape and the unchanged methacrylic' acid esters in the articles be converted, by suitable polymerization, into the solid final product.

It is also possible to start from solid, semi-solid, or plastic polymerization products of the methachylic acid esters, these being softened by heatingthem by themselves or with suitable solvents, their softenedstate. On c0014 ing or on the evaporation of the diluent, that may still be present, the product is converted into the solid lacquer form It is obvious fillers, and dyes, etc.

artificial stone, or the like be coated with the said syrupy solution orbe impregnated therewith, very resistant coating be mixed with comtriproplonln and tributyrin;

i that mixtures of various poly merized methacrylic acid esters can be used for lacquering, painting, or impregnating in accordance with this invention. It is likewise obvious that the wholly, or partly-polymerized esters can be mixed with suitable additional substances to modify the properties of the lacquering, painting,

or impregnating materials in any desired manner. As additions of this kind we mention oils (such,

for instance, as castor oil), dyes, powdered substances (such as'zinc oxide), camphor, camphor substitutes,- and the like.

In accordance with this'invention it'is possible to obtain valuable productsif the said polymers be dissolved, or softened, in suitable solvents and then be converted again to the solid state. The products thus obtained may be used for purposes for which cellulose esters have hitherto been used,

namely as substitutes for horn, amber, artificial resins, lacquers, for impregnation purposes, and

also for the production of films, interlayer for safety glass, pressure adhesives, artificial threads, and the like.

The products thu's over products made from nitrocellulose in being slow burning and odorless. By the addition of suitable agents, the strength and hardness of the products may be modified within wide limits so thatit is possible to manufacture both hard, horn-like substances and soft and morepliable products. The products may also bemodified by varying the conditions of the polymerization.

The monomer may be polymerized in the presence of a solvent and the solution used as such or the polymer recovered from. the solution by evaporation ,or precipitation methods. In. many cases,

' however, it is more profitableto use an amount of solvent insufficient to produce a freely flowing solution, so that soft plastic masses are obtained which can be pressed, kneaded, rolled, or drawn into shape, or formed in blocks, plates, or films.

- Plasticizers or other modifying agents may be added to the monpmer prior to polymerizationor directly to the polymerized product, it being genformed have the advantage erally desirable to employ'a plasticizer which is soluble in the polymer and the monomer, although it is not essential that the dual solubility characteristics be present. Thus, plasticizers or softening agents, such, for example, ascamphor,

phthalates, such as ethyl, propyl, isopropyl, butyl,

isobutyl, cycloherwl, methyl cyclohexyl, or benzyl phthalate, or phthalates of the mixed type such. as cyclohexyl butyl, benzyl butyl or butyl lauryl phthalate; esters ofother dibasic acids, such as the ethyl, propyl, isopropyl, butyl, isobutyl, cyclohexyL methyl cyclohexyl or benzyl esters of S110;-

ethanej halogenated hydrocarbons, such as chlorinated diphenyls and dichlordibenzyl; etherv compounds, such as dicresoxyethyl ether; and drying, non-drying or semi-drying 'oils, such as castor oil, cotton seed oil, linseed oil, and the like. These additions also facilitate later mechanical treatment, as cutting, sawing, and polishing.

The polymerizedestera mixtures of the polyw merized esters with dissimilar polymerizable esters or other polymerizable compounds of methacrylic or acrylic acids or vinyl compounds; or interpolymers of the esters with such other compounds may be used advantageously as safety glass interlayers. These polymerized esters, mixtures thereof, or inte'rpolymers thereof may be plasticized or otherwise modified as desired. The compositions maybe compounded with glass in an unpolymerized, partially polymerized, or completely polymerized condition. When compounding the safety glass with the unpolymerized or partially polymerized compositions, the polymerization may be effected by subjecting the sandproximately C. and holding it at that temperature until polymerization is substantially complete.

2. The polymeric methacrylic acid ester of an aliphatic monohydric sectionary alcohol prepared by polymerizing the monomeric ester in accord with the process of claim 1.

3. The polymeric diisopropyl carbine] meth-' acrylate prepared by polymerizi g the monomeric ester in accord with the process of claim 1.

4. The polymeric secondary butyl methacrylate prepared by polymerizing the monomeric ester in accord with the process of claim 1.

5. The molding composition comprising the polymeric methacrylic acid ester of an aliphatic monohydric secondary alcohol prepared by polymerizing the monomeric ester in accord with the process of claim 1.

6. .The interpolymer of a methacrylic acid ester of an aliphatic monohydric secondary alcohol and a polymerizable derivative of an acid selected from the group consisting of acrylic acid and methacrylic acid, which interpolymer is'prepared by polymerizing a mixture of the monomeric compounds in accord with the process of claim 1.

HAROLD J. BARRETT. 

